Patent Literature 1 describes a Fabry-Perot type semiconductor laser diode. An n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer are stacked in the m-axis direction. The n-type semiconductor layer includes an n-type GaN cladding layer and an n-type InGaN layer, and the p-type semiconductor layer includes a p-type GaN cladding layer and a p-type InGaN layer. A refractive index difference between the cladding layers and the optical guide layers is not less than 0.04. Patent Literature 2 describes a laser device with the emission wavelength of 425 nm-450 nm. Patent Literature 3 describes a laser device which achieves improvement in the aspect ratio of the far field pattern of emission. The p-side optical guide layer of this laser device has a striped protrusion and the emission wavelength of the device is in the range of 370 nm to 470 nm. Non-Patent Literature 1 describes an InGaN/GaN multiple quantum well structure grown on a (11-22) plane. Emission at the wavelength of 514 nm is obtained by optical pumping.